Manufacture of



Patented Oct- 16, 1945 MANUFACTURE OF 1.2.3.4:TE'1RAZOLE COLIPOUNDS John David Kendall, Ili'ord, England, assignor to mom Limited, Iiiord, England, a British com- No Drawing. Application December 11, 1944, Se-

flll No. 567,789. In Great Britain August 27,

10 Claims.

This invention relates to the manufacture of organic compounds and particularly to the manuiacture of 1.2.3.4-tetrazolecompounds, containing a hydrocarbon substituent in the 1-position and a mercapto group in the 5-position, and tautomers thereof.

The compounds with which this invention is concerned have the following tautomerlc iormulae (I): B-if c=s R-N-O s H an t where R is a substituted or unsubstituted hydrocarbon group, and the invention is also concerned with the production or the alkali metal salts of such compounds.

A known method of making such compounds consists in reacting a mustard oil of the formula RNOS (R having the significance given above) with sodium azide. However, the mustard oils are diificult to prepare and are expensive.

According to the present invention alkali metal salts of compounds or the tautomeric formulae (I) are prepared by reacting a dithiocarbamlc ester containing a hydrocarbon or substituted hydrocarbon substituent on the nitrogen atom (i. e. a compound 01, the generalformula R.NH.CSSR1 wherein R and R1 are each substituted or unsubstituted hydrocarbon groups) with an alkali metal azide, e. g. sodium azide. According to a further feature or the invention compounds of the tautomeric formulae (I) are prepared by acidifying solutions or the said alkali metal salts and separating the free tetrazole compounds.

x The reaction has been iound to be of quite general application. The group R can be an alkyl, aryl, aralkyl or cycloaliphatic group, e. g. a methyl, ethyl or higher alkyl group, a benzyl or naphthylmethyl group, a phenyl, naphthyl or di-phenyl group, or a cyclopentanyl or cyclohexanyl group. Such groups may themselves contain 'substituents, for example halogen atoms. nitro, amino, substituted amino, hydroxy, alkoxy and oxyalkyl groups.

In the course or the reaction a mercaptan RISK is split out and this forms a valuable byproduct for use in other processes. Since the group R1 does not occur in the product its precise nature is immaterial, and though it may be any or those referred to above in connection with the group R, its preferred from the point of view of ease of reaction and simplicity in preparing the thiocarbamic ester intermediate that it should be a lower alllyl group and preferably amethyl group.

The thiocarbamic ester intermediate is readily prepared by reacting a suitable amine of the formula R.NH: with carbon disulphide in the presence of a strong base yielding, tor example where caustic soda is used, a product of the formula R.NH.CSSNa, and then treating this with -an ester R1X where X is the residue of a strong acid, tor example a mineral acid or p-toluene sulphonic acid, whereby the desired intermediate of formula RNHDSSRi is formed. In the case where the group R contains an amino group, i. e. where a diamine such as p-phenylene diamine or benzidine is used a product which contains two NHCSSR1 groupings may be obtained so that a bis-tetrazole compound is formed.

The reaction to form the tetrazole compound is preferably eifected in the presence of a solvent Ior the reactants which does not take part in the reaction. A suitable solvent is aqueous ethyl alcohol, though any other substantially inert solvent or solvent mixture may be used.

The following examples illustrate the invention:

EXAMPLE 1 1-methz1l-5-mercapto-1.2.3.4-tetrazole 12.1 gm. of N-methyl dithiocarbamic acid methyl ester and 7 gm. of sodium azide were mixed in 30 cc. of ethyl alcohol and boiled under reflux.

Water was added to the extent necessary to bring all the azide into solution (about 15 cc.). The solution was then boiled for 1 hour, methyl mercaptan being evolved, and was then cooled in ice and acidified with hydrochloric acid. A small amount of solid which precipitated was filtered oil and rejected, and the filtrate was then concentrated to small bulk by heating on a water bath. On cooling, the l-methyl 5 mcrcapto-1.2.3.4- tetrazole crystallised out and was filtered off, washed with water to remove sodium chloride, and dried. It was a white solid and had a melting point of 124 C.

EXAMPLE 2 1 -phen11l-5 -mercapto-1 .2.3.4-tetrazole The general procedure of Example 1 was toliowed using 1.0 gm. 0! methyl dithiocarbanilate, 0.5 gm. oi. sodium azide and 20 cc. of aqueous ethyl alcohol ethyl alcohol). The product, after recrystallisation from ethyl alcohol, consisted of a white solid, melting point C.

Exam: 8

I-cpclohmrwl-S-nwrcopto-l 2.3.4-tetraeole 9.0 gm. of N-cyclohexanyl dithiocarhamic acid methyl ester (prepared by reacting cyclohexylamine with carbon disulphide in alkali solution,

treatingtheproductwhileinwater Exam 4 1 (o-methozu-ph'enyl) -5-mercapto-1.2.3.4-

tetrozole The general procedure 01' Example 3 was followed using 6.5 gm. of N-(o-methoxy-phenyl) dithiocarbamic acid methyl ester, 3.0 gm. of sodium azide and 40 cc. of aqueous ethyl alcohol (80% ethyl alcohol), the reaction mixture being refluxed for flve hours. After dilution with water, the reaction mixture was acidified, whereupon the desired product separated as a solid which, after washing with water and recrystallisation, was obtained as white needles, melting point 165 C. with decomposition.

Exams: 5

l p-chlor-phenyl) -5-mercapto-1 2.3.4-

tetrozole The general procedure of Example 4 was followed using 8 gms. of N-(p-chlor-phenyi) -dithiocarbamic acid methyl ester, 2.5 gm. of sodium azide and 40 cc. 01' aqueous ethyl alcohol (80% ethyl alcohol). Refluxing was continued for three hours. The product was obtained as a white crystalline solid, melting point 178' C.

Exams: 6 r-bml-s-mercamo-iau-mmoze 5 gm. of N-henzyl dithiocarbamic methyl ester, 2 gm. of sodium azide and 25 cc. of ethyl alcohol were refluxed together and cc. of water added. The sodium aside dissolved and methyl mercaptan was evolved. Alter refluxing for live hoursthe solution was cooled and diluted with water. The small amount of oil which was precipitated was extracted with ether leaving an aqueous solution otthesodhimsaltofthetetramle. Thissolution was acidified with concmtrated hydrochloric acid, when the tetraaole was precipitated. A small ether layer which formed was allowed to evaporate. The tetrasole was then removed by filtrationandtheliquoraevaporatedtosmallhulkto obtainasecondcrop. The combinedcropsot tetrazolewererecrystallisedirom soiuiioninllilqbaqueous ethylalcohol togivetheproduct aswhite crystalline flakes, melting point 144 0.

The product separated s,sso,seo

andthewhiteprecipitatefllteredofl'. Thisonrecrystallisation from dilute ethyl alcohol solution yielded the product, melting,porlnt 155-160 0., with decomposition.

I-fl-Mphthul-S-mercapto-I 2.3.4-tetmzole 5 gm. of N- (p-naphthyl) -dithiocarbamic methyl ester and 1.5 gm. 01' sodium aside were reacted asinExample'l,thewhitesolidobtained being recrystallised from dilute ethyl alcohol to yield the product, melting point 172 0., with decomposition.

What I claim is: 1. Process for the production at alkali-metal salts of compounds o! the general tautomeric formulae:

B-N-C=B a-N--c-su Hi i which comprises reacting a compound of the formula R-NH.CBSR1 where R and R1 are each a hydrocarbon nucleus, with an alkalimetal aside. 2. Process for the production of compounds of the general tautomeric formulae:

n-n---o=s BN-C8R mt l i which comprises reacting a compound or the form'ula RNECBSRi where R and R1 are each a hydrocarbon nucleus, with an alkali metal azlde, acidifying the resulting reaction mixture and separating the free tctrazole compound.

3. Process for the production of sodium salts of compounds oi the general tautomerlc tormulae:

N lllH 11.5 gm. of N-(a-naphthyl) -dithi0carbamic methyl ester and 5.0 gm. 0t sodium azide were refluxed together in aqueous ethyl alcohol solution for one hour. The solution was cooled, acidified,

which comprises reacting a compound of the formula ILNELCSSR: where R and R1 are each a hydrocarbon nucleus, with a sodium azide.

4. Process for the production of compounds oi the general tautomeric formulae:

N'\ l/ N which comprises reacting a compound of the formula RJHLCSSRr where R and R1 are each selected from the group comprising substituted and unsubstituted groups, with a sodium aside. acidifying the resulting reaction mixture and separating the free tetranole compound.

5. Process for the production 01 alkali-metal salts of compounds of the general tautomeric formulae:

which comprise reacting a compound or the {annals 8.83.0888: where R1 is a lower alkyl groupandR-isahydrocarbonnucleus, withan alkali metal side.

8. Process for the production oi compounds of the general tautomeric formulae:

a-n c=s RN- -G-BH mi N e,sse,soo

the general tautomeric formulae:

which comprises reacting a compound oi. the formula RNH.CSSRI. where R: is a methyl group and R is a hydrocarbon nucleus, with an alkali metal aside, acidifying the resulting reaction mixture and sep r ting the free tetrazoie compound.

9. Process for the production of alkali-metal salts of compounds of the general tautomeric formulae:

an N

which comprises reacting a compound of the formula RNI-LCSSR; where R1 is a lower alkyl group and R is a naphthyl group. with an alkali metal azide.

10. Process for the production of compounds of the general tautomeric formulae: R-l;Z---G=S s-u c-sa which comprises reactins a compound of the formula RNI-LCSSRr where R1 is a lower alkyl group and R. is a naphthyl group, with an alkali metal azide. acidifying the resultins reaction mixture and separating the free tetrazole compound.

JOHN DAVID IGZNDALL.

cERTiFIcArE 0F CORRECTION.

Patent Nos October 16, 1915.

JOHN DAVID KENDALL.

It is hereby certified that error appears in the of the above numbered patent requiring c printed specification orrection as follows: Page 2., sec- 0nd column, lines 5b. to 56 inclusive, strike out "selected from the group 0 omprising subs ti tuted of the case in the Patent Office.

Signed and sealed this 29th day of January,

(Seal) and unsubstituted hydrocarbon groups" and insert inhaid Letters Patent should be as conform to the record Leslie Frazer First Assistant Commissioner of Patents.

e,sse,soo

the general tautomeric formulae:

which comprises reacting a compound oi. the formula RNH.CSSRI. where R: is a methyl group and R is a hydrocarbon nucleus, with an alkali metal aside, acidifying the resulting reaction mixture and sep r ting the free tetrazoie compound.

9. Process for the production of alkali-metal salts of compounds of the general tautomeric formulae:

an N

which comprises reacting a compound of the formula RNI-LCSSR; where R1 is a lower alkyl group and R is a naphthyl group. with an alkali metal azide.

10. Process for the production of compounds of the general tautomeric formulae: R-l;Z---G=S s-u c-sa which comprises reactins a compound of the formula RNI-LCSSRr where R1 is a lower alkyl group and R. is a naphthyl group, with an alkali metal azide. acidifying the resultins reaction mixture and separating the free tetrazole compound.

JOHN DAVID IGZNDALL.

cERTiFIcArE 0F CORRECTION.

Patent Nos October 16, 1915.

JOHN DAVID KENDALL.

It is hereby certified that error appears in the of the above numbered patent requiring c printed specification orrection as follows: Page 2., sec- 0nd column, lines 5b. to 56 inclusive, strike out "selected from the group 0 omprising subs ti tuted of the case in the Patent Office.

Signed and sealed this 29th day of January,

(Seal) and unsubstituted hydrocarbon groups" and insert inhaid Letters Patent should be as conform to the record Leslie Frazer First Assistant Commissioner of Patents. 

